Do I Need Felt Paper Under Siding

Siding applied directly over tar paper creates a sandwich effect and can trap water between the siding material and the tar paper.

Do i need felt paper under siding.

Felt paper also commonly referred to as tar paper is an underlayment material applied to bare walls before siding is installed. That s because i believe that under certain circumstances felt outperforms housewrap. Should any water get past the siding properly installed felt paper. Over the years house wrap materials have advanced providing far more protection.

Basically all model codes agree on the need for a weather resistant barrier paper usually specified as 15 felt or grade d kraft paper behind stucco brick stone and other porous veneers. Felt labeled astm 15 meets specific standards and is the norm in many areas. The old practice of running felt strips under siding casing joints may actually be creating an environment more prone to rot by concentrating more moisture. Felt or building paper must be applied to walls properly to be effective.

This is a time intensive process and requires all sorts of skill. I ll stick with tried and true felt paper. Before delving into why you should have house wrap under your vinyl it is essential to understand what exactly house wrap is. I have seen literally hundreds of houses stripped of asbestos siding that had 15 felt under it.

The paper requirement is typically omitted for other types of siding when they re installed over rated structural sheathing. Install pieces in the correct order and make cuts carefully so any moisture can travel downward at all points without slipping under the wrap. But because the vinyl siding covers the felt paper it is shielded from the sun and never gets hotter than the temperature of the siding from solar gain. Tar paper does not offer this.

Decades ago the original form of house wrap used was asphalt coated felt paper. In fact many builders disagree on the effectiveness of house wraps altogether and while some builders will only install 15 pound asphalt saturated felt paper underneath exterior siding others swear by plastic fabric house wraps such as typar or tyvek. Many builders use standard 15 pound roofing felt. I ve opened up houses built less than 5 years previous and the tyvek was shreaded like old newspaper.